Oil sands are an increasingly important source of raw petroleum. Due to the solid nature of oil sands, extraction of crude oil from oil sands presents a variety of challenges. Some challenges are related to creating a crude oil from the oil sands that is suitable for transport via pipeline.
One option for removing the non-petroleum material is to first mix the raw product with water. For example, a water extraction process can be used to separate a majority of the non-petroleum material from the desired raw crude or bitumen. A water extraction process can remove a large proportion of the solid, non-petroleum material in the raw product. However, after the initial water extraction process, smaller particles of non-petroleum particulate solids will typically remain with the oil phase at the top of the mixture. This top oil phase is sometimes referred to as a froth. Separation of the smaller non-petroleum particulate solids can be achieved by adding an additional solvent to the froth of the aqueous mixture. This is referred to as a “froth treatment”. For example, a paraffinic solvent such as heptane can be added to the froth to cause a phase separation between an aqueous based phase and a bitumen phase. Unfortunately, due to the nature of the paraffinic solvent, a portion of the potential petroleum product is lost with the aqueous phase. The petroleum product lost with the aqueous phase may include a substantial portion of asphaltenes.
As an alternative to a water extraction, a non-aqueous extraction can be performed to separate crude oil from oil sands. Use of a non-aqueous extraction solvent can reduce or minimize the amount of water needed for extraction of crude oil from oil sands, and can potentially eliminate the need to perform a subsequent froth treatment. However, use of a non-aqueous extraction solvent can increase the amount of fine particulate matter that remains in the bitumen phase. The presence of an elevated content of fine particulate matter can create difficulties when attempting to transport such a non-aqueous extracted crude oil via pipeline.
U.S. Pat. No. 8,114,274 describes a method for treating bitumen froth with high bitumen recovery and dual quality bitumen production. The method includes using multiple gravity settling steps to separate phases containing bitumen in a hydrocarbon diluent from phases containing water, fine solids, and residual bitumen. Naphtha is provided as an example of a hydrocarbon diluent. One described advantage of the method is generation of a lighter bitumen stream that is suitable for transport by pipeline without further processing.
U.S. Published Patent Application 2012/0000831 describes methods for separating out a solvent feed after use in recovery of bitumen from oil sands. The method includes treating a bitumen froth with a paraffinic or naphthenic type diluent to produce bitumen and froth treatment tailings. Toluene is identified as a naphthenic type diluent that can improve bitumen recovery from tailings.
U.S. Published Patent Application 2014/0021103 describes methods for extracting bitumen from an oil sand stream. The method includes contacting the oil sand stream with a non-aqueous solvent and then screening the combined oil sand and solvent stream to form a screened oil sand stream and a rejects stream. Bitumen is then extracted from the screened oil sand stream.
U.S. Pat. No. 5,308,586 describes an electrostatic separator using a bead bed. The separator is described as being suitable for separating FCC catalyst fines from an FCC slurry oil. The electrostatic separator is periodically backflushed with additional treated slurry oil to remove particles from the separator. These backflushed particles are returned to the FCC reactor.